5bd3297fd4
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@4222 a1c6a512-1295-4272-9138-f99709370657
80 lines
2.5 KiB
C
80 lines
2.5 KiB
C
/***************************************************************************
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* __________ __ ___.
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* Open \______ \ ____ ____ | | _\_ |__ _______ ___
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* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
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* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
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* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
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* \/ \/ \/ \/ \/
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* $Id$
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*
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* Copyright (C) 2002 by Linus Nielsen Feltzing
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*
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* All files in this archive are subject to the GNU General Public License.
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* See the file COPYING in the source tree root for full license agreement.
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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* KIND, either express or implied.
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*
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****************************************************************************/
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#include "config.h"
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#include "sh7034.h"
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#include "kernel.h"
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#include "thread.h"
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#include "adc.h"
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/* This driver updates the adcdata[] array by converting one A/D channel
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group on each system tick. Each group is 4 channels, which means that
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it takes 2 ticks to convert all 8 channels. */
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static int current_group;
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static unsigned short adcdata[NUM_ADC_CHANNELS];
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static void adc_tick(void)
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{
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/* Copy the data from the previous conversion */
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if(current_group)
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{
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adcdata[4] = ADDRA >> 6;
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adcdata[5] = ADDRB >> 6;
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adcdata[6] = ADDRC >> 6;
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adcdata[7] = ADDRD >> 6;
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}
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else
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{
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adcdata[0] = ADDRA >> 6;
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adcdata[1] = ADDRB >> 6;
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adcdata[2] = ADDRC >> 6;
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adcdata[3] = ADDRD >> 6;
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}
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/* Start converting the next group */
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current_group = !current_group;
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ADCSR = ADCSR_ADST | ADCSR_SCAN | (current_group?4:0) | 3;
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/* The conversion will be ready when we serve the next tick interrupt.
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No need to check ADCSR for finished conversion since the conversion
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will be ready long before the next tick. */
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}
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unsigned short adc_read(int channel)
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{
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return adcdata[channel];
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}
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void adc_init(void)
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{
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ADCR = 0x7f; /* No external trigger; other bits should be 1 according
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to the manual... */
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/* Make sure that there is no conversion running */
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ADCSR = 0;
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/* Start with converting group 0 by setting current_group to 1 */
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current_group = 1;
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tick_add_task(adc_tick);
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/* Wait until both groups have been converted before we continue,
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so adcdata[] contains valid data */
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sleep(2);
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}
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